Long-Term Cover Cropping Suppresses Foliar and Fruit Disease in Processing Tomatoes.

While links between soil and plant health are implied, there are few opportunities to empirically evaluate this due to inherent differences among sites. An exception is a long-term experiment established in 2007 (repeated in 2008) in Ridgetown, ON, where improved soil health scores and changes in soil microbial communities were observed in the medium-term with annual cover crops (CC). This led us to hypothesize that CC-induced changes in soil health might affect bacterial spot (Xanthomonas hordorum pv. gardneri) and anthracnose (Colletotrichum coccodes) development in processing tomato. Five CC treatments (no CC control, winter cereal rye, oat, radish, and mix of radish + rye) planted after winter wheat harvest were evaluated in 2019 and 2020 (CC grown nine times over 12 years). Fruit yields and net revenue were similar or greater with CC than without. In 2019, there was greater defoliation (area under the disease progress stairs = 4,370 ± 204), percent red fruit (71.0% ± 5.38), and rots (1.91% ± 0.5) in no CC than with radish (3,410, 39.1%, and 0.62%, respectively, P ≤ 0.0366), indicating earlier fruit maturity in no CC plots. Similarly, no CC had a greater incidence of red fruits with anthracnose (25.8% ± 2.89) compared with all CCs but rye (7.4 to 12.1% ± 2.89; P = 0.0029). Environmental conditions in 2020 were less favourable for disease development. Defoliation was not affected by CC treatment (P = 0.1254), and anthracnose incidence was low (≥90.3 ± 1.22% healthy fruit), which may have limited the ability to detect treatment effects (P = 0.2922). Long-term cover crops have the potential to produce greater or equivalent tomato yield with decreased defoliation and anthracnose fruit rot.

Influence of cover crops at the four spheres: A review of ecosystem services, potential barriers, and future directions for North America.

Cover crops have been studied for over a century, but the recognition of a complex interaction of cover crop on the Earth's biosphere, lithosphere, hydrosphere, and atmosphere is relatively recent. Furthermore, previously published cover crop research has largely focused on evaluating cover crop impacts on subsequent crop yield. Understanding the cover crop-induced benefits on soil organic carbon (SOC) sequestration, nitrous oxide (N2O) emissions, wind and water erosion, weed control, and soil microbial communities has gained considerable attention in the last few decades, which is crucial to make progress towards developing sustainable agricultural production systems. New research is continuously published to gain a comprehensive understanding of the multiple ecosystem services provided by cover crops. Here, in this review, we aimed to (a) summarize current knowledge related to cover crop impacts on agroecosystem functioning and explore the potential mechanisms responsible for those effects, and (b) identify the key factors limiting the adoption of cover crops into agroecosystems and the conspicuous knowledge gaps in cover crop research. Overall, the review results suggest that cover crops increased subsequent crop yield, increased SOC storage, increased weed suppression, mitigated N2O emissions, reduced wind and water erosion, suppressed plant pathogens, and increased soil microbial activity and wildlife biodiversity. However, the magnitude of benefits observed with cover crops varied with cover crop type, location, and the duration of cover cropping. Notably, cover crop termination methods, designing crop rotations to fit cover crops, additional costs associated with cover crop integration, and uncertainty related to economic returns with cover crops are some of the major barriers limiting the adoption of cover crops into production systems, particularly in North America. In addition to long-term effects, future research on cover crop agronomy, breeding cover crop cultivars, and interactive effects of cover crops with other sustainable land management practices is needed.